This invention relates to a mechanism for non-destructively testing a gear type transmission. The mechanism comprises a vibration measuring device (e.g., a laser type sensor) positioned outside the gear case to measure the amplitude of vibrations induced in the gear case by unsatisfactory gear mesh actions. The mechanism further comprises speed measurement devices (e.g., tachometers) for measuring the rotational motion (r.p.m) of the shafts on which the gears are carried.
Both the vibration measuring device and the speed measuring devices are located outside the gear case. There is no need to dismantle the gear assembly, or to install the measuring devices within the gear case.
The proposed measuring system is somewhat similar to a measuring system disclosed in a paper prepared by Richard G. DeJong and Jerome E. Manning titled "Gear Noise Analysis Using Modern Signal Processing and Numerical Modeling Techniques", published by the Society of Automotive Engineers (SAE), paper No. 840478. Another system of interest is disclosed in an article by S.L. Shmater titled "Precision Measurement of Torsional Oscillations Induced by Gear Errors" on pp. 77 through 88 of a publication titled "The Shock and Vibration Bulletin" for June 1984, published by the Shock and Vibration Information Center, Naval Research Laboratory, Washington, D.C. U.S. Pat. No. 4,649,743 discloses another system for non-destructively testing gear type transmissions.
The proposed system differs from the above-referenced testing systems in regard to the parameters used for designating a gear fault. In the prepared system the time series averaged signal, synchonized to the relevant shaft speed, and variations thereof, are used to measure gear acceptability.